Loudspeaker enclosure



Sept. 10, 1957 o READ 2,805,729

LOUDSPEAKER ENCLOSURE Filed Sept. 15, 1953 2 Sheets-Sheet 2 INVENTOROLIVER READ ATTORNEY LOUDSPEAKER ENCLOSURE Oliver Road, Greenwich, Conn.Application September 15, 1953, Serial No. 380,239

12 Claims. (Cl. 181-31) The present invention relates to soundreproduction and more particularly to a loudspeaker enclosure used witha more or less conventional type of loudspeaker for high fidelityreproduction.

Heretofore sound reproduction equipment such as radios,

phonographs, and the like have been provided with loudspeakers and ahorn or loudspeaker enclosure for reproducing the sounds and it has beenthe desire of the manufacturers of these devices to obtain accuratesound reproduction of as high fidelity as possible. Although extensiveresearch has been done, the production models of speaker enclosures havenot been entirely satisfactory.

in homes of modest means where the cost of careful analysis by competentengineers and extensive experimentation is not practical quality soundreproduction has not been available. Due to difierent acousticcharacteristics of different rooms in which sound reproduction equipmentis used and also because of the limited available installationlocations, a single loudspeaker enclosure has not produced the optimumresults in all uses and the customer has had to be satisfied with lessthan the optimum quality of reproduction.

Engineers generally agree that the volume required for a 15-inchloudspeaker in an enclosed box should be at least 10 cubic feet for theinfinite battle type of loudspeaker enclosure. Such an enclosure mightbe objectionable from the amount of space required but if satisfactorysound reproduction can be accomplished in an enclosure of this type itwould be acceptable to the general public. No assurance can be had thatthe large enclosure will produce satisfactory results under allconditions and this can only be determined by actual use in the locationwhere the sound reproduction is to occur.

ln other installations an opening is provided in a closed cabinet toproduce the bass reflex type of loudspeaker enclosure. Although sometuning can be accomplished in existing bass reflex type loudspeakerenclosures by moving a shutter over the opening, the results have notbeen sufliciently satisfactory for all installations for generalacceptance.

The folded horn type of loudspeaker enclosure has been reasonablysatisfactory in installations at the corner of a room but has not beenentirely satisfactory in other locations.

As a result of the various types of loudspeaker enclosures in use, ithas not been possible to obtain the best quality of sound reproduction,particularly in the low pitched sound around and below 50 cycles. Alsoit has been necessary to test a number of different types of loudspeakerenclosures to obtain the most desirable quality for listenersatisfaction at the time of installation of the equipment. Since it hasnot been practical to do this careful experimentation at eachinstallation of sound reproduction equipment, results have not pleasedall customers.

In reproducing low frequency vibration, boominess has frequentlyoccurred and no practical means of elimihating this boomy sound has beenfound and conse- United States Patent Ofiice 2,805,729 Patented Sept.10, 1957 quently listeners have been accepting mediocre reproduction.

An object of the present invention is to overcome the difficultiesencountered with existing equipment by the provision of a loudspeakerenclosure of a general utility which is adapted to be controlled for thedesired listening pleasure of the user.

A further object of the present invention is to provide a soundreproduction unit for use with radios, phonographs, and the like forobtaining quality high fidelity reproduction of the sound.

Another object of the invention is to provide a loud speaker enclosurefor use with existing sound reproducing equipment and which loudspeakerenclosure may be adjusted to obtain the desired listener satisfaction ofreproduced sound.

Another object of the invention is to provide a loudspeaker enclosurewhich may be readily changed from one type to another by simpleadjustments which may be made by persons unskilled in the technicalaspects of the problem.

A further object of the invention is to provide a single loudspeakerenclosure which may have the sound reproducing characteristics ofseveral different types of sound reproducing structures and in which theuser may select the characteristics desired.

Another object of the invention is to provide a relatively inexpensiveloudspeaker enclosure which may be readily constructed from availablematerials and which loudspeaker can perform the functions of theinfinite baffle, bass reflex, or folded horn loudspeaker enclosure.

A further object is to provide suitable adjustments for a loudspeakerenclosure to accommodate for variables in location, use, and the like.

Briefly, the present invention relates to a cabinet type loudspeakerenclosure in which a cabinet having a top, bottom, sides, back, and afront is provided with a plurality of openings therein with a more orless conventional type of loudspeaker. A pair of partition wallsconverge from the front wall of the speaker toward the rear andterminate short of the rear while such converging walls are located onopposite sides of the loudspeaker. In one form of the invention theseconverging partitions may be hinged to vary the degree of convergence. Apair of partition walls extend from the rear of the cabinet forwardlyoutside of the converging walls and such second walls diverge forwardlytoward the front of the cabinet. The front of the cabinet is providedwith a central opening below the loudspeaker and an adjustable shuttercontrols the effective size of such opening. The front is also providedwith openings at the sides thereof adjacent to the partition walls and adoor is mounted on the cabinet at each of said side openings and suchdoor serves as a continuation of the forwardly diverging partition wallsto change the cabinet into a folded horn type enclosure. With the doorsclosing the side openings of the front and the shutter adjusted to atleast partially open position, a bass reflux type loudspeaker enclosureis obtained. If the shutter and doors are completely closed, an infinitebaflle type of loudspeaker enclosure is obtained. By using a V-type doordifferent effective volumes of the bass reflex and infinite battleenclosure can be obtained. Also by adjusting the hinged convergingportions different effective cubic volumes can be had and the ratio ofeffective cross section of the folded horn can be adjusted as de sired.

Further object and advantage of the invention will be apparent from thefollowing description taken in conjunction with the drawing, wherein:

Fig. 1 is a front view of one form of loudspeaker enclosure showing thedoors closed and the shutter in partially closed position;

Fig. 2, an enlarged section taken substantially on line 22 of Figure 1showing the !-type door in one position and a preferred means forhinging the same.

Fig. 3, a fragmentary section of a modification of the left doorconstruction showing an alternative means for hinging a V-type door;

Fig. 4, a fragmentary section of a modified door in which a single panelis used for obtaining the various effects;

Fig. 5, a fragmentary section of another form of single panel door withthe hinge construction therefor;

Fig. 6, an enlarged sectional view similar to Fig. 2 or a modificationin which the inner partition bafiles are hinged for angular adjustmentwith respect to the front of the cabinet;

Fig. 7, a fragmentary section taken substantially on the line 77 of Fig.6 showing one form of sealing means for the top and bottom edges of adoor panel;

Fig. 8, a section taken substantially on line 8-8 of Fig. 6 showing theseal betwen hinged baflie partition and the top and bottom of thecabinet; and,

Fig. 9, a modified form of seal which may be used on the doors or thepivoted baflies.

Referring more particularly to the drawing wherein like referencenumerals indicate like parts throughout, an all-purpose loudspeakerenclosure or cabinet includes a bottom panel 10, a top panel 11, sidepanels 12 and 13, a back panel 14, oblique corner panels 15 and 16 and afront panel 17. A circular opening 18 is formed in front panel 17 forregistry with a conventional loudspeaker 19, which may be of the dynamictype and such loudspeaker may be secured to the front panel in anysuitable manner.

The portion of the front panel 17 below the loudspeaker opening 18, isprovided with a rectangular opening 20, and the effective size of suchopening may be controlled by a shutter 21 of a size larger than theopening 20 and mounted on the inside of front panel 1'7 for verticaladjustment by means of bolts 22, passing through the shutter andslideably received in slots 23 formed in the panel 17. Suitable knobs 24are in threaded engagement with the bolts 22 and secure the shutter 21in any desired position of adjustment.

A pair of converging partition bafiie wall members 25, 26 extending fromthe top to the bottom of the cabinet project rearwardly from the sideedges of the front panel 17 terminating short of the rear panel of thecabinet with the loudspeaker 19 located therebetween.

A pair of diverging partition bafiie wall members 27, 28, extending fromthe top to the bottom of the cabinet project forwardly from the rear ofthe cabinet to a region adjacent the side edges of the front panel andthe sides of the cabinet. It will be noted that front panel 17 is ofapproximately less width than the spacing between side panels 12 and 13,thereby providing openings at each side edge of panel 17. The panelsforming the cabinet and the baffles may be secured together by means ofscrews, glue or the like.

The openings at each side edge of panel 17 may be closed by the -!-typedoors 29 and 29. The door 29 includes a front door panel 30 and a reardoor panel 31, fixed together to form a dihedral angle therebetween, andsuch dihedral angle is designed so that door panel 3!) closes theopening between'the adjacent side edge of front panel 17 and theadjacent front end of side panel 12. The rear door panel 31 closes theopening between the forward edge of baflie partition wall 27 and theforward end of side wall 12. The V-type door 29 is pivotally mounted onan axis 32 by means of pins projecting inwardly from the bottom and toppanels 19 and 11 into the V-typedoor 29, or by other suitable pivotmeans. The door 29 is similar to door 29 but made to fit the right sideof the cabinet. To obtain the desired sound tightness between the door29 and the adjacent panels and baffles, strips of felt 33 or similarmaterial may be glued or otherwise fastened to the side edges of thepanel 1'7 and to the for- Ward edge of baffle partition walls 27, 28 andalso to the top and bottom panels 11 and 10 respectively and thethickness of such strips will be such' as to produce the desired resultsaround the door. The edge of the door 29 adjacent side wall 12 is madetight by means of a narrow strip of felt 34 which is fixed to the insideof the forward end of side panel 12 and cooperates with a curved portion34 of the door for maintaining the proper seal. The frictional contactof the felt strip 34 with the curved portion 34 of door 29 also servesas a means for maintaining the door in its adjusted position. A suitableknob or handle 35 is provided for obtaining the desired adjustedcondition of the door 29.

The door 29 may be swung from the full line position shown in Fig. 2 ina counterclockwise direction to position A shown in dotted lines so thatthe door panel 3% becomes an extension of partition bafile wall 27thereby producing the folded horn type loudspeaker enclosure. it will beapparent that the right door 29 is similarly constructed for equivalentadjustments, but the motion would be in the opposite direction to thatof door 29.

The dotted line position shown at A of the V-type door 29 results in thedoor panel 39 being in alignment with baffie partition wall 27 therebyproviding the folded horn type speaker enclosure and a correspondingposition for door 29 is shown at A. The doors 29 and 29' may be moved tothe dotted line positions shown at B and B and in that position theentire space within the cabinet is in intercommunication and results inthe maximum efiective cubic volume of the loudspeaker enclosure. Whenthe doors are in the positions B and B, and the shutter 2i is closed acabinet of the infinite baflle type is obtained and with doors 29, 29 inthe positions B and B and shutter 2 open the bass reflex cabinet type ofenclosure is obtained with maximum cabinet cubic volume.

With doors 29, 2? in fuil line position an infinite bafiie typeenclosure of an effective volume within diverging portion walls 27, 28is obtained if shutter 23. is closed. With shutter 21 open and doors 2?and 29' in full line position reflex baflle type enclosure of reducedcubic content is obtained.

The folded horn arrangement with the doors in the positions A and A isparticularly desirable in corner locations and the oblique corner walls15 1e permit a speaker enclosure to be located in the corner of a roomWithout projecting excessively into the room and the sides f the roomform, in effect, a continuation-of the horn.

Although it has been found especially effective to use the doors 2? and29 in the positions shown in full lines, and dotted lines A, A and B, B,it is within the invention to adjust the doors to intermediate positionsas well as positionsin which the doors are opened to the maximum. Theadjustment of the doors can be made in accordance with the subjectivelistener satisfaction characteristics of the person using the equipment.It is therefore contemplated that various adjustments can be as desiredand one door may be arranged in one position and another door in adifferent position if desired.

Referring to Fig. 3, a side panel 36, a front panel 37 and partitionbafile walls and 39 correspond to elements 12, i7, 27 and 25 of thefirst embodiment and door 40 may be of the V-type having panels 41 and42 arranged to form a dihedral therebetween is mounted by means of ahinge 43 for pivotal movement in both directions as shown by arrowsdad-and 45. The hinge 43 may be of the piano type and the small spaceformed between the barrels of the hinge plates thereof may be sealed bya suitable tape 46 overlying the hinge. Sufiicient fullness of the tapeat the location of the hinge pin may be provided to permit the necessaryswinging movement of the door 40. The'ftape'may be made of flexibleresilient material if desired to stretch over the hinge pin when thedoor is opened to its outermost position.

Gaskets or felt sealing strips or the like may be propanels as well asthe free edge of the partition baffle wall 33 may be provided with asuitable sealing strip similar to Weatherstripping. If desired the feltstrip may be folded around the end of the partition bafile wall 38 asshown at 46 for additionally securing the felt strip in proper position.The strip may be secured by glue and/ or other fastening means such asnails, screws or the like, and the sidling strip may be applied to thetop and bottom and outer edge of each door.

Another modification of the invention is shown in Fig. 4 in which a sidepanel 47, a bottom panel 38, front panel 49, partition baftie walls 59and 51 are arranged in a similar relation to the corresponding elementsof the other modifications and a door 52 made of a single panel ispivotally mounted by means of pins or a rod 53 extending from the topand bottom panels into the door The door 52 may be provided with ahandle 5- 5 for moving such door from one position to another to obtainthe desired adjustment and sound characteristics by movement in eitherdirection as indicated by arrow 55. For 1 obtaining the desiredtightness of the door margins with the adjacent panels and bathe walls,suitable felt strips such as that shown at 56 may be provided forsealing the space between panel 49 and the door panel 52- and such feltstrip 56 may extend onto the partition bafrle wall 51 thereby sealingthe joint between baffle 51 and panel 49. A suitable strip of felt 57may be provided around the end of the partition baffle wall 50 and itwill be noted that the door panel 52 swings about pivot 53 and theadjacent edges of panel 49 and bathe cooperate for the proper degree ofscaled joint therebetween. A narrow strip of felt or other suitablepacking material 58 is secured to the side wall 47 and engages thearcuate rounded edge portion 58 of the door 52 and such strip materialserves to maintain the door 52 in any of its adjusted positions and alsoprovides the necessary tightness between the edge portion 53 of the door2 with the side of the cabinet. In this modification the door 52 may beswung to form a continuation of partition baffle wall 59 or may be swungto a position within the cabinet alongside of sidewall 47 and obviouslythe door could be opened to extend outwardly of the cabinet as desired.it will therefore be seen that in this modification of the invention asingle door of simple construction provides means to obtain the severalforms of loudspeaker enclosure by a simple adjustment.

A side panel 59 (Pig. 5), front panel 69 and partition bafile walls 61and 62 are arranged similar to the corresponding elements of the otherfigures and a door 63 hinged at 64 is movable from the full lineposition to 1.

the one dotted line position C in alignment with baflle wall 61 and alsomovable to another dotted line postiion D adjacent to the side panel 59and such door 63 being pivotally mounted to the side wall by means of apiano type hinge 64 or the like. In this modification suitable sealingmeans may be provided at the edges and top and bottom of the door ateach position as in the other modifications and it will be evident thatthe sealing strips may be of any suitable material which will producethe necessary tightness and in many cases the piano hinge 64 willprovide sufficient seal between the door 63 and the side panel 59, but,if desired, a strip of flexible material may be placed over the hingeand provided with sufiicient fullness to permit movement of the door 63.

Although the dimensions may be varied, it has been found that aloudspeaker enclosure of a height of 36", a depth of 17 /2", and a widthof 38% has been extremely satisfactory for use with a loudspeaker. Theouter walls of the cabinet are made of plywood with the battlepartitions made of /3 plywood. A suitable design for an 8" loudspeakercabinet enclosure is made to approximately half dimensions throughoutwith a 7 diameter cutout in the front panel for the speaker and suchcabinet may be made of /1 pine plywood. It will be evident that thedimensions may be varied and the are so located as to snugly 6 materialfrom which the cabinet is made can be selected from many availablematerials while obtaining many of the advantages of the presentinvention.

Strips or blocks of suitable sound insulating material such as Kimsulinsulation 65 may be arranged at random throughout the inside of thecabinet walls to prevent standing waves within the cabinet. Two inchKimsul insulation is shown at the apex of the born within the cabinetdirectly back of the speaker and the insulation is applied as necessary.

Braces (not shown) such as one inch by two inch strips may be added atrandom angles within the cabinet to offset tendencies towardobjectionable cabinet resonance.

Referring to Figures 6 to 8, inclusive, the cabinet enclosure mayinclude sidewalls 66 and 67, a back wall 68, oblique corner walls 69, 70and a bottom wall 71, a top wall 82, and a front panel 72. The frontpanel is provided with the usual loudspeaker opening as well as theshutter opening and a loudspeaker 73 is mounted thereon as well as ashutter 74 which may be similar to shutter 21 and similarly adjustable.

The front panel extends from the bottom 71 to the top wall 82 (Figs. 7to 9) but the side edges of the front wall 72 terminate short of thefront end of the side walls 66 and 67, providing openings therebetween.Partition baffle walls 75, 76 extend from the bottom wall of the cabinetto the top wall and partition baffle is hingedly mounted at its forwardedge by means of a piano type hinge 77 secured to the front panel 72 andto the partition baffle 75. interposed between partition bafile 75 andthe hinge plate '78 of hinge 77 is a strip of sealing material 79 suchas felt or the like which has an edge abutting the front panel 72 toprovide an airtight joint while permitting swinging movement of thepartition bafile 75 from a position shown in dotted lines at E to aposition shown in dotted lines at F and it will be understood that thestrip of felt or equivalent material has sufiicient resiliency tomaintain the proper tightness of seal for these various positions. Thepartition baffle 76 is similarly hinged at 80 and provided with the sameor equivalent type of seal to permit swinging movement of such partitionpanel 76 between the dotted line positions E and F and it may bepossible to adjust the partition baffies 75 and 76 in different angularpositions if desired. Referring to Figure 8 the partition baffle 75 isprovided with a rounded felt seal 81 at the top and bottom edges forengagement with the top wall 82 and the bottom wall 71 of the cabinetand the rounded sealing strips 81 may be made of felt or equivalentsuitable material to give the proper tightness.

In Figure 9 a modified seal for a bafiie 75 includes strips of felt orequivalent material 83 which may be secured to a side surface of thehinged partition 75 by any suitable means and such strips tightly pressagainst the bottom wall 71 and the top wall 82 to provide the desiredairtightness and also serving to maintain the hinged partition in itsadjusted position. It will be evident that partition 76 is similarlyprovided with sealing strips to obtain the desired tightness as well asto maintain the partition in its adjusted position.

Extending from the rear wall 68 are diverging partition bafile walls 84and 85 which extend from the bottom wall 71 to the top wall 82 andtoward the front end of the side walls 66 and 67 and terminating shortof such side Walls. These partition walls 84 and 85 are joined withtight joints at the rear wall and top and bottom walls by suitablemeans.

V-type doors 86 and 87 are pivotally mounted at the left and right sidesof the cabinet to close the openings at the side edges of the frontpanel. V-type door 86 includes a front panel 88 and a rear panel 89which are joined together to form a dihedral angle and are pivotallymounted by means of a pin or shaft 90 projecting from the top and bottomof the door and the portion of the door 91 adjacent the pivot 90 isrounded in an are about the side wall 66 for. maintaining an'airtightjoint'between the lportion291 .of the door and the front endof the sidewalled: A- strip 10f sealmaterial 93 ismounted'on the" free edge:ofeachidoor panelfiSand 89 and .alsoat the top and bottom edges of eachdoor panel thereby providing a sealbetween the front. panel 72,partition bafiie wall 34, bottomwall 81,. and topwa'll 82 of thecabinet.

it will be evident that -type doors'fi and 87 may be moved to the dottedline positions G and H as well as any'intermediate position and may beswung outwardly beyondthe position H if desired to completely open thecabinet loudspeaker enclosure.

V-type door-'37 also includes a front panel 94 and a rear panel 95 andhas similar types ofsealing strips along the edges thereof and such doormay be swungto various positions as desired by means of knob 6.

The hinged partition'b'aflle walls 75 and 76 may each be adjusted to itsdotted line position F thereby providing a small enclosure confining therear of the speaker therebetween and with the shutter 74 closed aninfinite-baffle type loudspeaker cabinet of small cubic volume isobtained and with the partition baffles still intheir position F withthe shutter open a bass-reflex type cabinet of small cubic volume isobtained.

A triangular block 96, which may be formed by sawing a 2" x 2 stripdiagonally is mounted on the rear wall '68 between the fixed bafilepartition walls 84 and 85 and a one inch layer of Kimsul or equivalentsound insulation is secured'around the projecting portion of thetriangular block. It will be understood that the triangular blockextends from the bottom to the top of the cabinet.

Assuming ii-type doors 86 and 87 are in the dotted line position'G, afolded-horn type of loudspeaker enclosure is obtained and the pivotedpartition bafile walls 75 and 76 may be adjusted to various intermediatepositions between positions E or F by means of knobs 98 and suchadjustment can be made until the desired acoustical properties have beenobtained. By properly adjusting the partition bafie walls 75 and 75 theobjectionable boomy sound obtained at low frequencies with some types ofloudspeakers can be appreciably reduced or entirely avoided.

It will also be evident that the effective cross section of the foldedhorn may be adjusted by the swinging movements of the partition bafflewalls 75 and 76 and the structure may closely approximate the trueexponential form of horn. Alsothe size of the throat of the horn may beadjusted to obtain desired results.

It will be evident thatsuitable sound insulating material may be appliedto the inner surfaces of the cabinet similar to that shown in Figure 2but such insulation is omitted in Figure 6 to simplify the drawing.

Although the dimensions may be varied the pivoted partition baffles 75and 76 are shown as being 17% instead of 16% for the modification shownin Figure 2 and satisfactory results have been obtained with structuresof these dimensions.

The relationship of the two partition bafile walls 75 and 76 to thestationary baflle Walls of the folded horn result in a form ofacoustical low-pass filter. In addition,

a change of horn-flare acts in some degree to simulate an exponentialhorn.

When adjustable partition bafi le walls 75 and 76 are widely spread toalmost engage the two stationary bafiie walls 84 and 85, the efiectivetaper of the horn flares become greater. if has been found desirable tohave both adjustable baffie walls similarly positioned.

When adjustable bafile walls 75 and 76 are nearly touching at their rearends or are nearly closed the sound path and the cavity within the areawill be greatly changed from the widely spaced position of the rearendsof theadjustable partition baffle walls. In effect, adjustable bafflewalls 75 and 76 provide a variable cavity formed by such baffies in thevarious positions.

It will be apparent that loudspeakers may individually or in multiple.Thus a low frequency loudspeaker, a mid-range speaker, and a highfrequency speaker may be used in reproducing sound to obtain;a,

desired efiect.

A description of one form of the invention, Written by the applicant,will appear in Radio 8: Television News? for October, 1953 on pages 67,176 and 177 and a copy thereof accompanies this application.

It will be obvious to those skilled in this art that various changes maybe made in the invention, without departing from tie spirit and scopethereof, and therefore the invention is not limited by that which isshown in the drawing and described in the specification but only asindicated in the appended claims.

What is claimed is: l. A unit for sound reproduction comprising acabinet of sufficiently large dimensions and open on the frontforobtaining the desired fidelity of reproduction, a central panel onthe front, a loudspeaker mounted on the central panel, a pair ofconverging baffie members extending from the front rearwardly andterminating short of the rear of the cabinet and confining theloudspeaker therebetween; the central front panel being provided with anopening,-

a shutter for said opening and means for adjusting the size of saidopening, a pair of diverging bafiles extending from the rear of saidcabinet forwardly and terminating short of the front of said cabinet andadjacent the side edges of said front panel, said front panel and thesides of said cabinet defining openings, a door pivotally mounted oneach side of said cabinet at the outer edge of each of said openings sothat each door may close the adjacent opening between the front paneland the side of the cabinet, said doors being swingable to positionsforming extensions of the adjacent bafile.

2. A loudspeaker enclosure for selective use as an infinite bafilecabinet, a folded horn cabinet or a bass reflex cabinet comprising acabinet of sufficient size to serve for each use, said cabinet includinga rear Wall and top and bottom Walls and being open at the front, acentral panel closing the front and leaving an opening at each sidethereof, a loud speaker mounted in said central panel, a pair of wallsextending from the top to the bottom of the cabinet andconverging fromthe front toward the rear and secured at their distant edges on theside'edges of said front panel and enclosing said loud speaker, saidconverging walls extending from the top to the bottom of the cabinet, apair of walls located outwardly of said converging walls and divergingtoward the front and se-. cured to the rear wall of said cabinet andprojecting forwardly toward the openings formed between said front paneland the sides of said cabinet, a closure means mounted on said cabinetadjacent each opening, said closure means serving to entirely close thecabinet from the exterior and alternatively to limit the effective sizeof the cabinet to the space between said diverging walls andalternatively to be moved to render the entire cabinet open to theexterior whereby said loudspeaker enclosure may be controlled to obtainthe desired characteristics.

3. A sound reproduction structure comprising a closed cabinet ofsufficiently large dimensions for obtaining the desired quality ofreproduction and having a frontincluding a front panel with a centralopening, and anopening at each side, a loudspeaker mounted on the frontpanel, a first pair of partition members extending fromthe top to thebottom and converging from the front rearwardly and terminating short ofthe rear of the cabinet andconfining the loudspeaker. therebetween, ashutter forsaid' central opening in the. front, and means for adjustingthe be used and terminating short of the front of said cabinet andadjacent the side openings, a door movably mounted on said cabinet atthe outer edge of each of said side-openings so that the door may closethe adjacent opening between the front and the side of the cabinet, eachdoor being movable to a position forming an extension of the adjacentdiverging partition extending from the rear of said cabinet.

4. A loudspeaker enclosure for selective use as an infinite bafilecabinet, a folded horn cabinet, a bass reflex cabinet or the like,comprising a cabinet of sufiicient size to serve for each use, saidcabinet including a rear wall and top and bottom walls and a front paneland being open in part at least at the front, a loudspeaker mounted inthe front, a pair of converging walls secured at their distant edges tosaid front panel enclosing said loudspeaker and extending the majorheight of the cabinet and terminating short of the rear, a pair ofdiverging walls located outwardly of said converging walls and securedto the rear wall of said cabinet and projecting forwardly toward theopen portion of said front, closure means mounted on said cabinetadjacent each open portion, said closure means serving to entirely closethe cabinet from the exterior and alternatively to limit the effectivesize of the cabinet to the space between said diverging walls, saidclosure means being movable to various positions of adjustment.

5. Sound reproduction equipment comprising a cabinet having enclosingwalls and an open front, a wall panel closing at least a portion of saidfront, a loudspeaker mounted on said panel, baffles projecting from someof the walls of said cabinet inwardly of such walls and normallyterminating short of other walls of said cabinet to providecommunicating spaces, means for selectively changing the effectivevolume of said cabinet by providing continuations of some of saidbaffles of said cabinet to said other walls thereby separating the spaceWithin said cabinet and changing the acoustic properties thereof.

6. Sound reproduction equipment comprising a closed cabinet having aloudspeaker therein with an opening for the loudspeaker, baffie means oflimited extent within said cabinet extending from the interior thereofto a location adjacent an outer wall, at least one door mounted in saidcabinet adapted for movement from a position adjacent said baflle meansforming a continuation of said baffie means and movable to a positionspaced therefrom.

7. A sound reproducing structure comprising a cabinet having an openingtherein, a door mounted on said cabinet for closing said opening, saiddoor being pivoted within its outline for swinging movement from open toclosed position, and a sealing gasket means mounted on one of said doorand cabinet for sealing the edges of said door when in closed position,at least a portion of said gasket means adjacent the pivot also servingas a friction latch for maintaining the door in selected positions.

8. A loudspeaker enclosure comprising a cabinet having a bottom, top,sides, and back, and being open on the front, a panel mounted on thefront for receiving a loudspeaker therein, said front panel terminatingshort of the side walls to provide openings adjacent each side wall, apartition baffle wall hingedly mounted on each side edge of said frontpanel for swinging movement whereby each baflle may be moved toward orfrom the other, a pair of diverging baffle walls extending from the rearwall outwardly of said swingable partition baffle walls, said divergingbaflle walls projecting toward the front edge of said side walls therebyforming a loudspeaker enclosure which may be adjusted to obtain desiredsound reproduction effects.

9. A sound reproduction enclosure comprising a top and bottom, divergingbaflie wall partitions extending from the top to the bottom, a frontpanel mounted intermediate the outer edges of said diverging battlewalls, means for supporting a loudspeaker in said panel, a pair ofconverging baffle wall partitions hingedly mounted on the side edges ofsaid front panel and extending toward the apex of said diverging walls,said converging walls being adjustable toward and away from each otherand against the adjacent diverging baffle wall.

10. A sound reproduction enclosure comprising a top and bottom,diverging bafile wall partitions extending from the top to the bottom, afront panel mounted intermediate the outer edges of said divergingbaffie walls, means for supporting a loudspeaker in said panel, a pairof convering baffle wall partitions hingedly mounted on the side edgesof said front panel and extending toward the apex of said divergingwalls, said converging walls bein" adjustable toward and away from eachother and against the adjacent diverging baffle wall, a triangular prismmounted in the apex of said diverging partition baffle walls with theapex of the prism extending toward said front panel, and soundinsulating material around said prism for preventing undesired tonesfrom being emitted from the enclosure.

11. A loudspeaker enclosure comprising a structure having a top, abottom, a back, sides and open at the front, a panel at least partiallyclosing the front and providing openings adjacent each side edge of saidfront panel, said front panel being provided with an opening in which aloudspeaker may be mounted, baffle partitions located on each side ofthe speaker 'and flaring outwardly from the back to the front, movablepartitions inwardly of said stationary partitions and generally flaringfrom the rear toward the front with the rear ends movable toward andfrom each other whereby the effective size of the throat formed betweensaid rear ends of the movable partitions may be varied and the crosssectional area between said movable and stationary baffle partitions canbe controlled to obtain the desired sound effects.

12. A loudspeaker enclosure for selective use as an infinite bafflecabinet, a folded horn cabinet, a bass reflex cabinet or the like,comprising a cabinet of sufficient size to serve for each use, saidcabinet including top and bottom walls and being open in part at leastat the front, a front panel at least partially closing said front, aloudspeaker mounted in the front panel, a pair of converging wallssecured at their distant edges to said front panel enclosing saidloudspeaker and extending the major height of the cabinet andterminating short of the rear, a pair of diverging walls locatedoutwardly of said convering walls and secured to the rear wall of saidcabinet and projecting forwardly toward the open portion of said front,clossure means mounted on said cabinet adjacent each open portion, saidclosure means serving to entirely close the cabinet from the exteriorand alternatively to limit the effective size of the cabinet to th spacebetween said diverging walls, said closure means being movable tovarious positions of adjustment.

References Cited in the file of this patent UNITED STATES PATENTS1,635,837 Haag July 12, 1927 1,865,550 Barrows et al. July 5, 19321,904,537 Round Apr. 18, 1933 1,967,223 Bostwick July 23, 1934 2,310,243Klipsch Feb. 9, 1943 2,544,742 Volf Mar. 13,1951 2,665,459 Lee Ian. 12,1954 FOREIGN PATENTS 641,718 Great Britain Aug. 16, 1950

